Selenium-Cultured Potamogeton maackianus in the Diet Can Alleviate Oxidative Stress and Immune Suppression in Chinese Mitten Crab (Eriocheir sinensis) Under Copper Exposure.

Selenium (Se) is an essential trace element for aquatic animals. The aquatic plant Potamogeton maackianus is an important natural food of Chinese mitten crab (Eriocheir sinensis). The aim of this study was to determine whether the antioxidant and immune responses of Chinese mitten crab are affected by including Se-cultured P. maackianus in the diet. Three groups of P. maackianus were cultured at levels of 0.02 mg/kg Se, 8.83 mg/kg Se, and 16.92 mg/kg Se, and the plants in these groups were used in experimental diets fed to crabs (dietary Se content of 0.05, 0.43, and 0.82 mg/kg, respectively). Compared with crabs in the 0.05 mg/kg group, those in the 0.82 mg/kg group showed significantly increased specific growth rate, protease and lipase activities, triglyceride and cholesterol contents, and Se content in the hepatopancreas and muscle (P < 0.05); increased activities of glutathione peroxidase, glutathione reductase, and catalase in the antioxidant system; increased transcript levels of MT (encoding metallothionein); and decreased malondialdehyde content (P < 0.05). At the end of the rearing experiment, the crabs in the different groups were exposed to copper (Cu2+) stress for 96 h. All the juvenile crabs in the 0.43 and 0.82 mg/kg groups survived 96 h of Cu2+ stress. Crabs in the 0.82 mg/kg group showed enhanced antioxidant responses under Cu2+ stress, increased transcript levels of MT and LYZ, and increased resistance. Therefore, supplementation of the diet of Chinese mitten crab with increased levels of Se-cultured P. maackianus can reduce oxidative stress under Cu2+ exposure, activate the immune response, and benefit growth.

Color Doppler velocity profile and contrast-enhanced ultrasonography in assessment of liver cirrhosis.

BACKGROUND: This study was designed to probe the clinical value in assessing the degree of liver cirrhosis by using the arrival time of contrast agent in the right portal vein in contrast-enhanced ultrasonography, as well as the velocity and flow volume in the right portal vein using the color Doppler velocity profile technique. METHODS: Twenty-eight patients with HBV post-hepatic cirrhosis were grouped into compensated (13 patients) and decompensated cirrhosis (15); 30 patients without hepatic cirrhosis served as controls. Written informed consent was obtained from each patient. All the patients with hepatic cirrhosis were pathologically confirmed by percutaneous biopsy. SonoVue was injected to detect the arrival time in the right portal vein. The velocity and flow volume in the right portal vein were measured. The value of each parameter was compared for correlation analysis. RESULTS: The arrival time in the right portal vein in the cirrhosis group was much longer than that in the control group (24.92+/-1.34 vs. 20.81+/-0.55 sec, respectively, P<0.01). The mean velocity, maximal velocity and flow volume in the cirrhosis group were much lower than those in the control group (10.64+/-0.84 vs. 14.78+/-0.71 cm/sec, 13.68+/-1.02 vs. 17.30+/-0.68 cm/sec and 358.72+/-23.63 vs. 438.61+/-16.86 ml/min, respectively, P<0.01). With the development of cirrhosis, the arrival time in the right portal vein was longer (P<0.05), and the velocity and flow volume was lower (P<0.01). There was a negative correlation between arrival time and mean velocity, maximal velocity and flow volume in the right portal vein in the cirrhosis group (r=-0.547, P<0.01; r=-0.508, P<0.05; r=-0.471, P<0.05, respectively). CONCLUSIONS: With the development of liver cirrhosis, the arrival time of contrast agent in the right portal vein is gradually prolonged, whereas the velocity and flow volume in this vein decreases markedly, and there is a negative correlation between the results of the two methods.

Detection of local polarity of alpha-lactalbumin by N-terminal specific labeling with a new tailor-made fluorescent probe.

To detect the local polarity such as the N-terminal domain of a protein molecule, 3-(4-chloro-6-hydrazino-1,3,5-triazinylamino)-7-(dimethylamino)-2-methylphenazine has been designed and synthesized as a polarity-sensitive fluorescent probe by using an s-triazine ring as a backbone, neutral red and hydrazine as a polarity-sensitive fluorophore, and a labeling group, respectively. The fluorescence properties of the probe have been characterized. The probe has the following features: (1) stable in various solvents; (2) the long-wavelength emission of >550 nm that can avoid the interferences of the background fluorescence shorter than 500 nm from common biomacromolecules; and (3) the maximum emission wavelength (lambda(em)) sensitive to solvent polarity only but not to pH and temperature. The hydrazino group in such a probe reacts readily with an active carbonyl produced by transamination of a protein molecule, leading to N-terminal specific attachment of the fluorophore and thereby allowing the monitoring of local polarity. With this probe, the polarity of the N-terminal domain in both native and heat-denatured alpha-lactalbumin has been first determined, which corresponds to that with a dielectric constant of about 16, and the hydrophobic core near the N-terminus is found to be conservative for heating. The present strategy may provide a general method to study the local environmental changes of a protein molecule under different denaturation conditions.

Isolation and characterization of phenanthrene-degrading Sphingomonas paucimobilis strain ZX4.

Phenanthrene-degrading bacterium strain ZX4 was isolated from an oil-contaminated soil, and identified as Sphingomonas paucimobilis based on 16S rDNA sequence, cellular fatty acid composition, mol% G + C and Biolog-GN tests. Besides phenanthrene, strain ZX4 could also utilize naphthalene, fluorene and other aromatic compounds. The growth on salicylic acid and catechol showed that the strain degraded phenanthrene via salicylate pathway, while the assay of catechol 2,3-dioxygenase revealed catechol could be metabolized through meta-cleavage pathway. Three genes, including two of meta-cleavage operon genes and one of GST encoding gene were obtained. The order of genes arrangement was similar to S-type metapathway operons. The phylogenetic trees based on 16S rDNA sequence and meta-pathway gene both revealed that strain ZX4 is clustered with strains from genus Sphingomonas.

[Diversity of microbial genes in paddy soil stressed by cadmium using DGGE].

Variations of diversity of microbial genes in submerged paddy soil stressed by heavy metal cadmium were studied using modern molecular biotechnology which includes directly extracting total DNA from paddy soil, amplifying 16S rDNA and their V3 variable region by PCR, the denaturing gradient gel electrophoresis (DGGE). Two methods for extraction and purification of microbial DNA were compared. Bacterial communities were quantified by analyzing the DGGE band patterns. The genetic clusters and correlative comparison of bacterial communities were analyzed based on the DGGE finger-print. The results showed that there are some significant differences between bacterial communities in paddy soils treated with different concentrations of cadmium. The information about effect of cadium on microbial population based on molecular biological techniques are conformed with that from traditional methods, but that obtained about variations of microbial genes in paddy soil is much more than results based on the latter methods. It could provide a new way and foundation to research microbial gene diversity in contaminated environment.